REF: now possible to input gradientStep
REF: now possible to input gradientStep

Former-commit-id: 921471fa5370d7bf876dc684db3b4bab8c7e7882 [formerly 2f07b45455e5dba2dbfac59a36a2bf26372f3b05]
Former-commit-id: 1f1cab680276bed4b9b1f7ac4efda305b059651a
Former-commit-id: 004e57cc2e6965cf25be27387a7b2fae909d0674
neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox,neuropoly/spinalcordtoolbox